Electro copper plating additive and electro copper plating bath

ABSTRACT

Provided are an additive for electro copper plating and an electro copper plating bath containing the additive, wherein the additive forms a plating film uniformly in a range of from a low current density portion to a high current density portion and thereby gives good glossiness, and is not consumed at the time of non-usage thereof. In the present invention, an additive for electro copper plating including a block polymer compound expressed by the following general formula (1) is added to an electro copper plating bath. (Here, in the formula, R represents an alkyl group or an alkenyl group having a linear-chain or branched-chain structure and having a carbon number of 1 to 15, m is an integer of from 1 to 30, and n is an integer of from 1 to 40.)

FIELD OF THE INVENTION

The present invention relates to an electro copper plating additive and an electro copper plating bath, particularly relates to an electro copper plating additive suitable as a brightener for a copper sulfate plating bath and an electro copper plating bath containing the additive. The present application asserts priority rights based on JP Patent Application 2011-070667 filed in Japan on Mar. 28, 2011. The total contents of disclosure of the patent application of the senior filing date are to be incorporated by reference into the present application.

BACKGROUND OF THE INVENTION

To provide a glossy copper plating film, a brightener has been conventionally added to an electro copper plating bath. As the brightener, for example, organic thio compounds and high molecular organic compounds containing oxygen have been known. (Refer to PTL 1 or 2, for example.) As the organic thio compounds, disulfide compounds, such as NaO₃SC₃H₆S—SC₃H₆SO₃Na, have been widely used, while, as the high molecular organic compounds containing oxygen, oxyalkylene polymer, polyethylene glycol, polypropylene glycol, and the like have been used.

Furthermore, as a brightener other than the above-mentioned compounds, there has been used a polymer obtained by adding an ethylene oxide to a polypropylene glycol and expressed by the following general formula:

H-(EO)a-(PO)m-(EO)b-H

wherein EO represents an oxyethylene group, PO represents an oxypropylene group, and n=a+b.

However, these brighteners, which have been conventionally used, do not provide sufficient glossiness and do not have throwing power in a low current density portion of a copper plating film, whereby a rough film is formed. The cause for this is that, for example, the polymer expressed by the above-mentioned general formula has a molecular structure in which (PO)m, a hydrophobic group, is sandwiched between (EO)n on both sides, and therefore the effect of a hydrophobic group is weakened. As a result, when a compound comprising this polymer was used as a brightener for an electrolytic copper plating bath, current distribution was disturbed in a low current density portion and a high current density portion, and therefore uniform electrodeposition was disturbed, and accordingly poor plating, such as occurrence of minute pits and clouding, was caused.

Also, a brightener which is easily managed and not consumed when not in use is desired for electro copper plating.

PRIOR-ART DOCUMENTS Patent Document

-   PTL 1: Japanese Patent Application Laid-Open No. 2005-194608 -   PTL 2: Japanese Patent Application Laid-Open No, 2008-297221

SUMMARY OF THE INVENTION

The present invention is proposed in view of such conventional actual circumstances, and aims at providing an additive for electro copper plating and an electro copper plating bath containing the additive, the additive forming an uniform plating film in a range of from a low current density portion to a high current density portion and thereby providing good glossiness, and not being consumed at the time of non-usage thereof.

The present inventors earnestly studied to achieve the above-mentioned aim, and, as a result, found that when a block polymer compound having a higher effect of a hydrophobic group is used as an additive, a plating film is uniformly formed in a range of from a low current density portion to a high current density portion and thereby good glossiness can be provided, and completed the present invention.

In other words, an additive for electro copper plating according to the present invention comprises a block polymer compound expressed by a following general formula (1):

(wherein R represents an alkyl group or an alkenyl group having a linear-chain or branched-chain structure and has a carbon number of 1 to 15, m is an integer of from 1 to 30, and n is an integer of from 1 to 40.)

An electro copper plating bath according to the present invention contains the additive comprising the block polymer compound expressed by the above-mentioned general formula (1).

Effects of Invention

According to the present invention, the additive enables plating film to form uniformly in a range of from a low current density portion to a high current density portion and to provide good glossiness, and also the additive is not consumed when not in use, whereby a good and stable plating film can be formed.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an additive for electro copper plating and an electro copper plating bath containing the additive according to the present embodiment will be explained in detail.

The additive for electro copper plating according to the present embodiment comprises a block polymer compound expressed by a following general formula (1).

Here, in the general formula (1), R represents an alkyl group or an alkenyl group having a linear-chain or branched-chain structure and having a carbon number of 1 to 15, m is an integer of from 1 to 30, and n is an integer of from 1 to 40.

Examples of R which is an alkyl group or an alkenyl group having a linear-chain or branched-chain structure and having a carbon number of 1 to 15 include a methyl group, an ethyl group, an n-propyl group, an allyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, a 1-methylhexyl group, a 2-ethylhexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, and an n-pentadecyl group.

Furthermore, m and n in the general formula (1) may be suitably set in accordance with the above-mentioned type of R. Specifically, as a carbon number of R increases, hydrophobicity increases accordingly, and therefore by adjusting molar ratios of m and n in accordance with the type of R, the additive can have appropriate solubility in a plating bath. Also, m and n may be preferably set so that a molecular weight of the block polymer expressed by the above-mentioned general formula (1) is 500 to 2000.

As shown in the above-mentioned general formula (1), this additive has a structure in which one end at the side of an oxypropylene group is capped with an alkyl group or an alkenyl group. Thus, by capping an end of an oxypropylene group with an alkyl group or an alkenyl group, the oxypropylene group can have a higher effect as a hydrophobic group.

Furthermore, the additive shown in the above-mentioned general formula (1) has a fixed sequence of an oxypropylene group (PO) and an oxyethylene group (EO), and is a block polymer constantly having a structure of R—O—(PO)m-(EO)n-H. Thus, the oxypropylene group ((PO)m), whose end is capped with an alkyl group or an alkenyl group as mentioned above, allows a portion of “R—O—(PO)m” in the above-mentioned general formula (1) to act together as a hydrophobic group, whereby high hydrophobicity is provided.

An effect expected from this is such that a hydrophobic group of a compound is generally extruded from the water to an interface, and hence, when a plated material is immersed in an solution, a plated surface of the plated material becomes an interface, and the additive having high hydrophobicity is condensed on the plated surface, whereby an effect of the additive is increased. As a result, it is considered that an effect of the additive is exerted throughout from a low current density portion to a high current density portion, whereby a uniform plating film is formed and accordingly good glossiness can be provided.

Furthermore, such block polymer enables appropriate solubility to be provided thereto by the oxyethylene group at the other end of the structure of the additive; allows a polymer compound to be satisfactorily dissolved in an electro copper plating bath and also to be maintained stably in the plating bath; and control the chronological consumption when electrolysis treatment is not in use.

The block polymer compound expressed by the above-mentioned general formula (1) can be manufactured by the following method, for example. That is, under an atmosphere of inert gas, such as nitrogen gas, an alkyl alcohol or an alkenyl alcohol having a carbon number of 1 to 15 is first made to undergo an addition reaction with propylene oxide. After the addition reaction with propylene oxide, ethylene oxide is next added to induce an addition reaction with the ethylene oxide, whereby the block polymer compound is obtained.

Thus, an alkyl alcohol or an alkenyl alcohol having a carbon number of 1 to 15 is made to undergo an addition reaction with propylene oxide, and then ethylene oxide is added and reacted to carry out synthesis, whereby there can be produced the block polymer compound having a block unit with a certain structure in which (EO)n is added to (PO)m capped with an alkyl group or an alkenyl group.

A reaction temperature in the method of manufacturing the block polymer compound is not particularly limited, but preferably 90 to 160 degrees C. With a reaction temperature of not less than 90 degrees C., an appropriate reaction rate can be realized and thereby addition reactions with propylene oxide and ethylene oxide can be made to occur efficiently. On the other hand, with a reaction temperature of not more than 160 degrees C., formation of a side reaction product and the like is controlled, whereby a yield of a block polymer compound to be formed can be increased. Note that, in the addition reaction of an alkyl alcohol with propylene oxide and the subsequent addition reaction with ethylene oxide, it is preferable that, after the addition reaction with propylene oxide at the above-mentioned temperature of 90 to 160 degrees C., cooling is performed and then the addition reaction with ethylene oxide is carried out under the same temperature condition.

Furthermore, a reaction time is not particularly limited and different depending on a reaction temperature, but preferably within 15 hours in each of the addition reactions with propylene oxide and with ethylene oxide. With a reaction time of not more than 15 hours, formation of a side reaction product and the like is controlled, whereby a yield of a block polymer compound to be formed can be increased.

Furthermore, the addition reactions are preferably carried out under pressure, and a pressure at the time of starting an addition reaction is preferably 2 to 5 kg/cm².

When a block polymer compound expressed by the above-mentioned general formula (1) is used as an additive for electro copper plating, an addition concentration at this time is preferably 0.05 to 1.0 g/L. With an addition concentration of not less than 0.05 g/L, a plating film having sufficient glossiness can be formed. On the other hand, with an addition concentration of not more than 1.0 g/L, a current density range effectively available is prevented from becoming narrow, and a good plating film can be uniformly formed in a range of from a low current density portion to a high current density portion.

Next, there will be explained an electro copper plating bath to which an additive comprising the above-mentioned block polymer compound expressed by the general formula (1) is added, and explained a plating treatment using the electro copper plating bath. The electro copper plating bath is not particularly limited, but a copper sulfate plating bath is especially preferable. By adding the above-mentioned block polymer compound to a copper sulfate plating bath, a copper plating film having excellent glossiness can be uniformly formed in a wide range of current density, and the copper sulfate plating bath can be suitably used as a plating bath for decorative plating.

Specifically, the copper sulfate plating bath may be, for example, a plating bath having a basic composition comprising 50 to 250 g/L of copper sulfate (Cu₂SO₄.5H₂O) and 50 to 250 g/L of concentrated sulfuric acid. Note that the copper sulfate plating bath is made to usually contain a very small amount (approximately 10 to 200 mg/L) of chloride ions. Specifically, chloride ions can be contained, for example, by adding water-soluble chloride, such as NaCl.

Note that a known additive may be further added to the above-mentioned electro copper plating bath to further improve glossiness and smoothness. Specifically, for example, an organic thio compound, organic acid amides, an oxygen-containing high molecular weight organic compound, or the like can be added.

A condition of the plating treatment using the above-mentioned electro copper plating bath is a pH of not more than 1. Furthermore, a plating temperature in a range of 20 to 50 degrees C. and a cathode current density of 0.1 to 8 A/dm² are preferable. Furthermore, a copper plate or an insoluble anode may be used as an anode. Furthermore, in order to form a plating film having more uniform glossiness, it is preferable that agitation, such as air agitation or cathode rocking, is sufficiently carried out.

A material to be plated for which the above-mentioned plating treatment is provided is not particularly limited, but, for example, in order to perform decorative plating for a material to be plated, such as plastics, an electro copper plating bath to which the above-mentioned additive is added may be suitably used. Note that other materials, such as a printed-circuit board and electrical and electronic components, each having through-holes, may be subjected to the plating treatment. Thus, the electro copper plating bath to which the above-mentioned additive is added can be widely applied for decorative use to functional purpose.

EXAMPLES

Hereafter, specific examples according to the present invention will be explained. Note that the present invention is not limited to any of the following examples.

In each example explained below, a block polymer (R—O—(PO)m-(EO)n-H) shown in Table 1 was synthesized, and plating treatment was performed using a copper plating bath to which the block polymer compound was added as an additive, and then a plating film precipitated and formed was evaluated. Note that air was blown into the copper plating bath to perform sufficient agitation, in particular, air was blown against a material to be plated so that the vicinity of a cathode was agitated.

TABLE 1 Block Polymer (R—O—(PO)m-(EO)n-H) R Carbon Number m:n Example 1 n-propyl 3 15:15 Example 2 allyl 3 15:15 Example 3 n-butyl 4 10:15 Example 4 n-hexyl 6  5:20 Example 5 2-ethylhexyl 8  3:25 Example 6 dodecyl 12  2:30

Example 1 Synthesis of Block Polymer

In an airtight reaction vessel, 600 g (10 mol) of n-propanol and 5.6 g (0.1 mol) of potassium hydroxide were taken, and under a nitrogen gas atmosphere, subjected to an addition reaction with 870 g (15 mol) of propylene oxide at 90 to 130 degrees C. under a pressure of 2 to 5 kg/cm². After completing the addition reaction with the propylene oxide, the reaction vessel was cooled, and then 660 g (15 mol) of ethylene oxide was added thereto and reacted under the same conditions.

Next, 50 g of a synthetic adsorbent (Kyoward 600, manufactured by Kyowa Chemical Industry Co., Ltd.) was added to the reaction vessel and agitated at 70 degrees C. for 30 minutes, and then filtered, whereby 2070 g of polyoxyethylene (15) polyoxypropylene (15) propyl ether was obtained.

(Plating Treatment and Plating Film Evaluation)

Copper sulfate (Cu₂SO₄•5H₂O) 200 g/L Concentrated Sulfuric Acid 50 g/L NaCl 115 mg/L

To a copper sulfate plating solution comprising the above composition, 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polyoxyethylene (15) polyoxypropylene (15) propyl ether synthesized as mentioned above were added as additives to make a plating bath, and by using the thus obtained plating bath, plating treatment was performed with a Hull cell tester at a total current of 2 A for 10 minutes. Note that conditions of the plating treatment were pH<1, a temperature of 25 degrees C., and a cathode current density of 0.15 to 4 A/dm².

As a result, a precipitate having good glossiness was uniformly formed in a range of from a low current density portion to a high current density portion.

Furthermore, also in the case where plating treatment was performed in the same manner after a copper plate was put into the above-mentioned Hull cell tester and left therein overnight, a precipitate having good glossiness was uniformly formed as is the case with the first plating treatment. Hence, it was found that the additive was stably maintained without being consumed even at the time of non-usage thereof.

Example 2 Synthesis of B lock Polymer

In an airtight reaction vessel, 580 g (10 mol) of allyl alcohol (2-propen-1-ol) and 5.6 g (0.1 mol) of potassium hydroxide were taken, and under a nitrogen gas atmosphere, subjected to an addition reaction with 870 g (15 mol) of propylene oxide at 90 to 130 degrees C. under a pressure of 2 to 5 kg/cm². After completing the addition reaction with the propylene oxide, the reaction vessel was cooled, and then 660 g (15 mol) of ethylene oxide was added thereto and reacted under the same conditions.

Next, 50 g of a synthetic adsorbent (Kyoward 600, manufactured by Kyowa Chemical Industry Co., Ltd.) was added to the reaction vessel and agitated at 70 degrees C. for 30 minutes, and then filtered, whereby 2050 g of polyoxyethylene (15) polyoxypropylene (15) allyl ether was obtained.

(Plating Treatment and Plating Film Evaluation)

In Example 2, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polyoxyethylene (15) polyoxypropylene (15) allyl ether synthesized as mentioned above were added as additives.

As a result, a precipitate having good glossiness was uniformly formed in a range of from a low current density portion to a high current density portion. Furthermore, also in the case where plating treatment was performed in the same manner after a copper plate was put into the above-mentioned Hull cell tester and left therein overnight, a precipitate having good glossiness was uniformly formed as is the case with the first plating treatment.

Example 3 Synthesis of Block Polymer

In an airtight reaction vessel, 740 g (10 mol) of n-butanol and 5.6 g (0.1 mol) of potassium hydroxide were taken, and under a nitrogen gas atmosphere, subjected to an addition reaction with 580 g (10 mol) of propylene oxide at 90 to 130 degrees C. under a pressure of 2 to 5 kg/cm². After completing the addition reaction with the propylene oxide, the reaction vessel was cooled, and then 660 g (15 mol) of ethylene oxide was added thereto and reacted under the same conditions.

Next, 50 g of a synthetic adsorbent (Kyoward 600, manufactured by Kyowa Chemical Industry Co., Ltd.) was added to the reaction vessel and agitated at 70 degrees C. for 30 minutes, and then filtered, whereby 1920 g of polyoxyethylene (15) polyoxypropylene (10) butyl ether was obtained.

(Plating Treatment and Plating Film Evaluation)

In Example 3, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polyoxyethylene (15) polyoxypropylene (10) butyl ether synthesized as mentioned above were added as additives.

As a result, a precipitate having good glossiness was uniformly formed in a range of from a low current density portion to a high current density portion. Furthermore, also in the case where plating treatment was performed in the same manner after a copper plate was put into the above-mentioned Hull cell tester and left therein overnight, a precipitate having good glossiness was uniformly formed as is the case with the first plating treatment.

Example 4 Synthesis of Block Polymer

In an airtight reaction vessel, 1020 g (10 mol) of n-hexanol and 5.6 g (0.1 mol) of potassium hydroxide were taken, and under a nitrogen gas atmosphere, subjected to an addition reaction with 290 g (5 mol) of propylene oxide at 90 to 130 degrees C. under a pressure of 2 to 5 kg/cm². After completing the addition reaction with the propylene oxide, the reaction vessel was cooled, and then 880 g (20 mol) of ethylene oxide was added thereto and reacted under the same conditions.

Next, 50 g of a synthetic adsorbent (Kyoward 600, manufactured by Kyowa Chemical Industry Co., Ltd.) was added to the reaction vessel and agitated at 70 degrees C. for 30 minutes, and then filtered, whereby 2130 g of polyoxyethylene (20) polyoxypropylene (5) hexyl ether was obtained.

(Plating Treatment and Plating Film Evaluation)

In Example 4, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polyoxyethylene (20) polyoxypropylene (5) hexyl ether synthesized as mentioned above were added as additives.

As a result, a precipitate having good glossiness was uniformly formed in a range of from a low current density portion to a high current density portion. Furthermore, also in the case where plating treatment was performed in the same manner after a copper plate was put into the above-mentioned Hull cell tester and left therein overnight, a precipitate having good glossiness was uniformly formed as is the case with the first plating treatment.

Example 5 Synthesis of Block Polymer

In an airtight reaction vessel, 1300 g (10 mol) of 2-ethylhexanol and 5.6 g (0.1 mol) of potassium hydroxide were taken, and under a nitrogen gas atmosphere, subjected to an addition reaction with 174 g (3 mol) of propylene oxide at 90 to 130 degrees C. under a pressure of 2 to 5 kg/cm². After completing the addition reaction with the propylene oxide, the reaction vessel was cooled, and then 1100 g (25 mol) of ethylene oxide was added thereto and reacted under the same conditions.

Next, 50 g of a synthetic adsorbent (Kyoward 600, manufactured by Kyowa Chemical Industry Co., Ltd.) was added to the reaction vessel and agitated at 70 degrees C. for 30 minutes, and then filtered, whereby 2500 g of polyoxyethylene (25) polyoxypropylene (3) 2-ethylhexyl ether was obtained.

(Plating Treatment and Plating Film Evaluation)

In Example 5, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polyoxyethylene (25) polyoxypropylene (3) 2-ethylhexyl ether synthesized as mentioned above were added as additives.

As a result, a precipitate having good glossiness was uniformly formed in a range of from a low current density portion to a high current density portion. Furthermore, also in the case where plating treatment was performed in the same manner after a copper plate was put into the above-mentioned Hull cell tester and left therein overnight, a precipitate having good glossiness was uniformly formed as is the case with the first plating treatment.

Example 6 Synthesis of Block Polymer

In an airtight reaction vessel, 1860 g (10 mol) of 1-dodecanol and 5.6 g (0.1 mol) of potassium hydroxide were taken, and under a nitrogen gas atmosphere, subjected to an addition reaction with 116 g (2 mol) of propylene oxide at 90 to 130 degrees C. under a pressure of 2 to 5 kg/cm². After completing the addition reaction with the propylene oxide, the reaction vessel was cooled, and then 1320 g (30 mol) of ethylene oxide was added thereto and reacted under the same conditions.

Next, 50 g of a synthetic adsorbent (Kyoward 600, manufactured by Kyowa Chemical Industry Co., Ltd.) was added to the reaction vessel and agitated at 70 degrees C. for 30 minutes, and then filtered, whereby 3200 g of polyoxyethylene (30) polyoxypropylene (2) dodecyl ether was obtained.

(Plating Treatment and Plating Film Evaluation)

In Example 6, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polyoxyethylene (30) polyoxypropylene (2) dodecyl ether synthesized as mentioned above were added as additives.

As a result, a precipitate having good glossiness was uniformly formed in a range of from a low current density portion to a high current density portion. Furthermore, also in the case where plating treatment was performed in the same manner after a copper plate was put into the above-mentioned Hull cell tester and left therein overnight, a precipitate having good glossiness was uniformly formed as is the case with the first plating treatment.

Comparative Example 1 Plating Treatment and Plating Film Evaluation

In Comparative Example 1, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polyethylene glycol were added as additives; and a plating film thereby precipitated and formed was evaluated. Note that, also in this Comparative Example 1 and the following Comparative Examples 2 and 3, air was blown into the copper sulfate plating bath and agitation was sufficiently carried out.

As a result, the precipitate had good glossiness, but minute pits and white clouding were caused and the precipitate was not formed uniformly in a range of from a low current density portion to a high current density portion, and thus the plating film had a poor appearance.

Comparative Example 2 Plating Treatment and Plating Film Evaluation

In Comparative Example 2, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of polypropylene glycol were added as additives; and a plating film thereby precipitated and formed was evaluated.

As a result, the precipitate had good glossiness, but minute pits and white clouding were caused and the precipitate was not formed uniformly in a range of from a low current density portion to a high current density portion, and thus the plating film had a poor appearance.

Comparative Example 3 Plating Treatment and Plating Film Evaluation

In Comparative Example 3, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of block polymer (H-(EO)a-(PO)m-(EO)b-H, wherein m=17, and n=a+b=9) obtained by adding ethylene oxide to polypropylene glycol were added as additives; and a plating film thereby precipitated and formed was evaluated.

As a result, the precipitate had good glossiness, but minute pits and white clouding were caused and the precipitate was not formed uniformly in a range of from a low current density portion to a high current density portion, and thus the plating film had a poor appearance.

Comparative Example 4 Plating Treatment and Plating Film Evaluation

In Comparative Example 4, plating treatment was performed using a Hull cell tester with the same manner as in Example 1, except that there was used a copper sulfate plating bath to which 10 mg/L of bis-(ω-sulfopropyl)-disulfide disodium salt, 50 mg/L of diazotized diethyl safranine, and 0.2 g/L of random polymer obtained by simultaneously adding ethylene oxide and propylene oxide to n-butanol were added as additives, and a plating film thereby precipitated and formed was evaluated.

As a result, the precipitate had good glossiness, but was a stepped-surface plating which was precipitated with a step-like change, and plating was not precipitated in a low current density portion, and thus the plating film had a poor appearance. 

1. An additive for electro copper plating, comprising a block polymer compound expressed by a following general formula (1):

wherein R represents an alkyl group or an alkenyl group having a linear-chain or branched-chain structure and having a carbon number 1 to 15, m is an integer of from 1 to 30, and n is an integer of from 1 to
 40. 2. The additive for electro copper plating according to claim 1, wherein the block polymer compound is obtained in such a manner that, under an atmosphere of inert gas, an alkyl alcohol or an alkenyl alcohol having a carbon number of 1 to 15 is made to undergo an addition reaction with propylene oxide, and then ethylene oxide is added and reacted.
 3. An electro copper plating bath containing the additive for electro copper plating according to claim
 1. 